Liu Wei, Krump Nathan A, MacDonald Margo, You Jianxin
Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
J Virol. 2018 Jan 30;92(4). doi: 10.1128/JVI.01610-17. Print 2018 Feb 15.
Merkel cell polyomavirus (MCPyV) is the first polyomavirus to be associated with human cancer. Mechanistic studies attempting to fully elucidate MCPyV's oncogenic mechanisms have been hampered by the lack of animal models for MCPyV infection. In this study, we examined the ability of MCPyV-GFP pseudovirus (containing a green fluorescent protein [GFP] reporter construct), MCPyV recombinant virions, and several MCPyV chimeric viruses to infect dermal fibroblasts isolated from various model animals, including mouse (), rabbit (), rat (), chimpanzee (), rhesus macaque (), patas monkey (), common woolly monkey (), red-chested mustached tamarin (), and tree shrew (). We found that MCPyV-GFP pseudovirus was able to enter the dermal fibroblasts of all species tested. Chimpanzee dermal fibroblasts were the only type that supported vigorous MCPyV gene expression and viral replication, and they did so to a level beyond that of human dermal fibroblasts. We further demonstrated that both human and chimpanzee dermal fibroblasts produce infectious MCPyV virions that can successfully infect new cells. In addition, rat dermal fibroblasts supported robust MCPyV large T antigen expression after infection with an MCPyV chimeric virus in which the entire enhancer region of the MCPyV early promoter has been replaced with the simian virus 40 (SV40) analog. Our results suggest that viral transcription and/or replication events represent the major hurdle for MCPyV cross-species transmission. The capacity of rat dermal fibroblasts to support MCPyV early gene expression suggests that the rat is a candidate model organism for studying viral oncogene function during Merkel cell carcinoma (MCC) oncogenic progression. MCPyV plays an important role in the development of a highly aggressive form of skin cancer, Merkel cell carcinoma (MCC). With the increasing number of MCC diagnoses, there is a need to better understand the virus and its oncogenic potential. However, studies attempting to fully elucidate MCPyV's oncogenic mechanisms have been hampered by the lack of animal models for MCPyV infection. To pinpoint the best candidate for developing an MCPyV infection animal model, we examined MCPyV's ability to infect dermal fibroblasts isolated from various established model animals. Of the animal cell types we tested, chimpanzee dermal fibroblasts were the only isolates that supported the full MCPyV infectious cycle. To overcome the infection blockade in the other model animals, we constructed chimeric viruses that achieved robust MCPyV entry and oncogene expression in rat fibroblasts. Our results suggest that the rat may serve as an model to study MCV oncogenesis.
默克尔细胞多瘤病毒（MCPyV）是首个被发现与人类癌症相关的多瘤病毒。由于缺乏MCPyV感染的动物模型，试图全面阐明MCPyV致癌机制的机理研究受到了阻碍。在本研究中，我们检测了MCPyV-GFP假病毒（含有绿色荧光蛋白[GFP]报告基因构建体）、MCPyV重组病毒粒子以及几种MCPyV嵌合病毒感染从各种模式动物分离得到的真皮成纤维细胞的能力，这些模式动物包括小鼠（）、兔子（）、大鼠（）、黑猩猩（）、恒河猴（）、白掌猴（）、普通绒毛猴（）、红胸髭狨（）和树鼩（）。我们发现MCPyV-GFP假病毒能够进入所有测试物种的真皮成纤维细胞。黑猩猩真皮成纤维细胞是唯一支持MCPyV基因大量表达和病毒复制的细胞类型，而且其支持程度超过人类真皮成纤维细胞。我们进一步证明，人类和黑猩猩真皮成纤维细胞都会产生具有感染性的MCPyV病毒粒子，这些病毒粒子能够成功感染新的细胞。此外，在用一种MCPyV嵌合病毒感染大鼠真皮成纤维细胞后，该细胞支持MCPyV大T抗原的大量表达，在这种嵌合病毒中，MCPyV早期启动子的整个增强子区域已被猴病毒40（SV40）类似物取代。我们的结果表明，病毒转录和/或复制事件是MCPyV跨物种传播的主要障碍。大鼠真皮成纤维细胞支持MCPyV早期基因表达的能力表明，大鼠是研究默克尔细胞癌（MCC）致癌过程中病毒癌基因功能的候选模式生物。MCPyV在一种极具侵袭性的皮肤癌——默克尔细胞癌（MCC）的发展过程中起重要作用。随着MCC诊断病例数的增加，有必要更好地了解这种病毒及其致癌潜力。然而，由于缺乏MCPyV感染的动物模型，试图全面阐明MCPyV致癌机制的研究受到了阻碍。为了确定开发MCPyV感染动物模型的最佳候选者，我们检测了MCPyV感染从各种既定模式动物分离得到的真皮成纤维细胞的能力。在我们测试的动物细胞类型中，黑猩猩真皮成纤维细胞是唯一支持MCPyV完整感染周期的分离细胞。为了克服其他模式动物中的感染障碍，我们构建了嵌合病毒，这些病毒在大鼠成纤维细胞中实现了MCPyV的有效进入和癌基因表达。我们的结果表明，大鼠可能是研究MCV致癌作用的模型。
